__author__ = 'thoth'


import bpy
from mathutils import *


def adjust_handle_right(bpoint):
    bpoint.handle_right = bpoint.co * 2 - bpoint.handle_left


def set_handles(bpoint, dx, dy, dz):
    bpoint.handle_right = bpoint.co + Vector([dx,dy,dz])
    bpoint.handle_left = bpoint.co - Vector([dx,dy,dz])


def make_bezier_helix(name, radius, dz, cycle_count):

    curve = bpy.data.curves.new(name, 'CURVE')
    curve.dimensions = '3D'

    bez = curve.splines.new('BEZIER')

    after_helix = 4 * cycle_count
    final_length = after_helix +1
    bez.bezier_points.add(final_length - len(bez.bezier_points))

    for bp in bez.bezier_points:
        bp.handle_left_type = 'FREE'
        bp.handle_right_type = 'FREE'

    # this is a popular approximation of a circle
    handle_delta = radius * .552
    for i in range(cycle_count):
        bp0 = bez.bezier_points[i*4]
        x = radius
        y = 0
        z = (i)*dz
        bp0.co = (x,y,i*dz)
        set_handles(bp0, 0, handle_delta, dz/12)

        bp1 = bez.bezier_points[i*4+1]
        x = 0
        y = radius
        z = (i+0.25)*dz
        bp1.co = (x,y,z)
        set_handles(bp1, -handle_delta,0, dz/12)

        bp2 = bez.bezier_points[i*4+2]
        x = -radius
        y = 0
        z = (i+0.5)*dz
        bp2.co = (x,y,z)
        set_handles(bp2, 0, -handle_delta, dz/12)

        bp3 = bez.bezier_points[i*4+3]
        x = 0
        y = -radius
        z = (i+0.75)*dz
        bp3.co = (x,y,z)
        set_handles(bp3, handle_delta,0, dz/12)

    bp = bez.bezier_points[after_helix]
    x=100
    y = -radius
    z = dz*(cycle_count -0.25) + x/(handle_delta) * dz/12
    bp.co = (x,y,z)
    set_handles(bp, handle_delta, 0, dz/12)

    return curve

def mission1(scn, radius, dz, cycle_count):
    name = "helix"
    obj = bpy.data.objects.get(name)
    curve = make_bezier_helix(name, radius, dz, cycle_count)
    if obj is None:
        obj = bpy.data.objects.new(name, curve)
    else:
        obj.data = curve
    try:
        scn.objects.link(obj)
    except:
        pass

#

scn = bpy.context.scene
mission1(scn, 2, 12, 5)